I admit I was paranoid about parvo but I couldn't find a small box of puppy pads anyway. The box I found on Amazon was like 60 pads or something. Before the trip I used duct tape on the backside to make larger pads that were 2 x 2 normal pads in size. As it turns out my little guy decided to poop and pee in between places I could stop on the interstate. He didn't wait for me (obviously) so he just did it in his crate. Not ideal but we dealt with it.
The parvo risk is real though. Two different vets gave me the advice of "just put him in the crate and drive straight home". I only had a 9 hour drive but still. When I asked for alternatives, one vet said if I really had to take him out "just drive into a farm field with no livestock". That seemed a little extreme but when a vet tells you to drive your car offroad and into someone's property ... well, that seemed serious to me.